An RDS method is known, wherein traffic messages, in a coded form and identifying the relevant location(s), are transmitted simultaneously with the radio program. A radio receiver with a decoder receives an audio program, as well as the coded and digitized traffic information. In contrast to the ARI system (U.S. Trademark Reg. No. 1,282,281, owned by Bosch subsidiary Blaupunkt Werke GmbH), the radio does not interrupt the current audio program. Instead, the radio stores the coded traffic information and, when a key is activated, outputs it visually, by means of an output device, or acoustically by means of speakers.
Furthermore, a device is known from German Published Patent Application DE-OS 39 36 577, Duckeck & Bragas, and corresponding U.S. Pat. No. 5.303,401,issued Apr. 12, 1994, which device determines the position of the radio receiver by comparing the received transmission frequencies with frequency tables stored for various regions.
It is also known from Bosch Technische Berichte [Bosch Technical Reports] (Vol. 8, issue 1/2 of 1986, pages 15 ff, entitled "Transmission of Coded Traffic Bulletins over FM stations using RDS") that, after the exact travel route has been entered, the driver has an opportunity to have a computer select the traffic information relating to the entered travel route.
In the latter method, it is necessary to establish a definite travel route before starting. This system also requires a special coding process, in accordance with which the roads and places along the travel route must be identified and entered by the driver. Furthermore, there is no chance for the driver to monitor the traffic situation along another travel route and to use an alternate travel route, if warranted by the traffic conditions.